You want another melee ADC assassin type champion? Play yasuo... Yasuo is exactly that. Fiora was meant to be a fighter and her old kit was not that. Now with the rework she is what she should be. Also, if you build her full offence, you can delete even an alistar when his ult is on.... Get 520+ AD and each vital does more than 25% max hp true damage... I have done it... She is a bit harder to build that much damage because she takes a bit more skill to play, but, watching her fight is just a spectacle. Try my build if you want, it is
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depending your needs for lifesteal. My runes are kind of basic, Armor pen marks, AD/lvl quints, Armor/lvl seals, 3 cdr/lvl glyphs and 5 mr/lvl glyphs. 21/9/0 masteries with all the ad and pen you can get plus the 5% cdr and blade and spell weaving for the bonuses because you always use your spells and those masteries are good for that kind of dueling. That build is for the games that you have already pulled ahead and you don't need much defence. As a defensive item i recommend
both for the mr and the active and for the high amount of AD. With that setup you have 40% cdr @lvl18, an absurd amount of AD, your passive really hurts, very high mobility due to the swiftness boots and the weaker slows on you and a lot of armor pen. The IE is a very good choice if you don't need much lifesteal because it synergizes beautifully with your E, making that crit really painful for your target. So, late game you end up becoming a beast that deletes anyone you come across. Also, the ult scales with your AD so the more your AD, the stronger the heal. If they have a lot of lockdown cc, i suggest getting a Qss asap and making the mercurial instead of the IE or BT. All three of them give the same amount of AD so you won't lose any offensive power while you instead become a lot harder to lock down. Personaly i always go for the mercurial. Also, In lane, depending on your opponent, you should build first either the cleaver or the hydra but in any case those 2 should be your first items. If you think about it, you will understand how strong you are in the late game. Also, If you lane against a Darius, i recommend you go for a cleaver and then a Qss.... That Qss is the worst counter for him because all the power in Darius lies in his passive... Deny his passive, deny his power.
Try it and let me know what you think.
EDIT: They must have nerfed her because now her passive scales with her bonus AD instead of her Total AD, so the numbers are a bit off... So, instead of 25% max HP true damage, you should do about 20% max HP true damage with the build i described. Which is still 80% of the target's HP in true damage if you hit all four vitals. Any squishy will die with 2 hits on a vital while everyone else will die just by hitting all of their vitals, no matter how tanky they are. your AAs combined with the true damage is enough to kill any target regardless of their defences.